Use a graph model and a path in your graph, as in Exercise 64, to solve the jealous husband's problem. Two married couples, each a husband and a wife want to cross a river. They can only use a boat that can carry one or two people from one shore to the other shore. Each husband is extremely jealous and is not willing to leave his wife with the other husband, either in the boat or on shore. How can these four people reach the opposite shore?